I attended the ASM General Meeting in New Orleans this week and soaked up some science and some amazing New Orleans cuisine. I also loaded up on vendor tchotchkes. While browsing around the vendor booths I managed to acquire no fewer than FOUR bottles of hand sanitizer. After reading the latest in mBio, I'm glad I did.
Walsh and Camilli's study on Streptococcus pneumoniae may send you on a cleanliness rampage, too: the pathogen (pneumococcus) can survive dessication on surfaces and retains its ability to infect even after long periods of time.
S. pneumoniae is one of the leading culprits behind ear infections, pneumonia and meningitis, and it often makes its home in the nasopharynx (way in the back of your sinuses), where it can get along as a commensal or switch over to the pathogenic way of life. Although other respiratory pathogens have been known to spread by contact with fomites (infected objects), until now, scientists had thought that S. pneumoniae was transmitted solely person-to-person via “respiratory droplets” from coughing or sneezing. Walsh and Camilli tell us otherwise. They smeared S. pneumoniae on polystyrene surfaces and recovered it after it dried out. Not only did the bacterium survive at least four weeks of dryness, it preserved the ability to go on to infect some poor unsuspecting soul (in this case, a mouse). Since knockout mutants did so even without a polysaccharide capsule, dessication tolerance doesn’t depend on a capsule.
And in a nice news-you-can-use aspect of the paper, the authors review prior studies of the numbers of streptococci expelled during nose blowing, and the numbers of cells recovered from the hands of infected individuals who forgo handwashing for three hours. There are plenty of cells on used handkerchiefs and hands to transfer to an uninfected person. Now, where are those little bottles of hand sanitizer...?